Adam Benhamama, 3, went missing in Laval, Que., on Sunday. (Laval police)

Laval, Que., police say they have done all they can do to find a missing boy with autism and have ended their search and recovery mission.

Adam Benhamama, 3, has been missing since Sunday after he was last seen playing with his older sister at the home of a family friend.

Police believe he fell into the frigid waters of the Mille-Îles River, which runs just metres behind the home in the Auteuil neighbourhood of the city, north of Montreal.

The father had just stepped inside the house for a few minutes when his daughter rushed in to say that Adam was nowhere to be seen.

"We've done all we could do as far as the ground search and the river," said Laval police Const. Nathalie Lorrain.

Parents use GPS to track son with autism

The case of Adam Benhamama has highlighted the challenge some families face in keeping tabs on their children with autism.

Some parents are reaching out to technology. Melanie Chartrand and Patrice Rodier said their son Felix, who could not speak, would often wander away when he was a young boy.

Rodier, a computer technician, came across an early personal GPS tracking devices and had a brainwave.

"I saw that, and then, of course, I thought of my son," said Rodier.

He has since created his own GPS system and paired it with a computer mapping software. Rodier sells the pair for about $300.

Even though Felix is older, the family still uses the GPS when in crowded places.

"This would be to use if something did happen. You don't want something happening," he said.

Electra Dalamagas of Autism Montreal said a GPS device cannot replace proper parental supervision.

"The device doesn't have the judgment or capacity to stop a child from doing something," she said.

Divers using sonar had searched the river for days but by nightfall on Wednesday they had come up empty-handed.

"There was no clue whatsoever, nothing has turned up — no piece of clothing, absolutely nothing," said Lorrain.

Lorrain said investigators will discuss Thursday if there is anything else they can do besides wait for the boy's body to surface.

Police explain misinformation

Early on in the search for the boy, police said Adam was deaf, unable to speak and was autistic. Investigators said his health condition made the search effort more difficult.

However, the Benhamama family has confirmed through a friend that the boy was only hearing impaired and was capable of limited speech.

His form of autism was also mild, the family said.

Police explained the discrepancies Wednesday, saying the misinformation came from a hectic 911 call from the home.

"[The operator] asked the question if the child spoke French. The answer that was given to us is that he is deaf and can't speak," said Lorrain.

Police do not believe the misinformation affected the search.